I've noticed that the heat of the day and the sun-baked hot roads don't affect my tire pressure too much. Granted I've never taken a measurement, but I have left my house with a little less air than I like (judging only by feel), thinking that the heat will cause them to expand. However, as I check my tires periodically during the ride I've noticed that they feel about the same; I'm sure the pressure went up some, although I can't detect that increase by simply squeezing the tire, so I'm a little skeptical about the heat bursting a tire. At least not with out some other contributing factors.